1. Field of the Invention
The present invention relates to a microwave oven, and more particularly to a safety device for a microwave oven which is operated in accordance with the opening/closing status of a door of the microwave oven to selectively connect a power supply with a driving circuit.
2. Description of the Prior Art
Generally, a microwave oven is a device for cooking/warming food by using microwaves, and has the advantage that it cooks various kinds of foods within a short period of time while keeping the original texture of the foods.
A conventional microwave oven is shown in FIG. 1. Referring to FIG. 1, the conventional microwave oven has a cabinet 10 which is divided into a cooking chamber 10a and a device chamber 10b. The cooking chamber 10a receives the food to be cooked therein, and a door 30 is mounted on the front side of the cooking chamber 10a. Various electric components 22a, 22b, 22c, 22d are arranged in the device chamber 10b for generating the microwaves for cooking the desired food, and a control panel 40 is formed on the front side of the device chamber 10b.
However, there is the possibility that the microwave oven can be operated without the door 30 being completely closed, and the microwaves radiated into the cooking chamber 10a may leak outside, harming the user. In order to prevent such a dangerous use, a safety device is essentially required for the microwave oven to selectively control the operation of the microwave oven by detecting the opening/closing status of the door 30. FIG. 2A shows the safety device of a conventional microwave oven.
Referring to FIG. 2A, the safety device of the subject conventional microwave oven includes a first switch 41, a second switch 42, and a third switch 43, all of which are formed on a door latch 12 of the device chamber 10b, and a door key 37 having a pair of key switch portions 37a and 37b formed on the door 30 for operating the contact points of the first, second, and third switches 41,42, and 43.
The first switch 41 is arranged near the end of a first guide portion 13a, and the second and third switches 42 and 43 are arranged near the end of a second guide portion 13b. Between the second guide portion 13b and the third switch 43, a switch lever 44 is disposed such that it is pivoted on a hinge axis 44a. The first, second, and third switches 41, 42, and 43 selectively connect a power supply (not shown) with a driving circuit (not shown) of the microwave oven.
As the user closes the door 30, the pair of key switch portions 37a and 37b of the door key 37 are inserted into a pair of insert holes 12a and 12b of the door latch 12, and are guided along the guide portions 13a and 13b, respectively. Accordingly, by the second key switch portion 37b, the switch lever 44 is pivoted, and the contact point of the third switch 43 is operated. When the door 30 is completely closed, as shown in FIG. 2B, the pair of key switch portions 37a and 37b are moved downward by a spring 37c, so that the contact points of the first and second switches 41 and 42 are operated. Only when the contact points of the first, second, and third switches 41, 42, and 43 are operated, the power supply (not shown) is connected to the driving circuit (not shown).
In the event that the door 30 is incompletely closed and any contact point of the first, second, and third switches 41, 42, and 43 is not in operation, the power supply (not shown) can not make contact with the driving circuit (not shown), and as a result, the microwave oven can not be turned on.
According to the safety device of the subject conventional microwave oven, however, the third switch 43, which is located in the innermost part of the device chamber 10b, is positioned to be operated indirectly via the switch lever 44. Therefore, a space for the switch lever 44 between the second key switch portion 37b and the third switch 43 is needed, and the length L of the door latch 12 is lengthened.
As the length L of the door latch 14 is lengthened, the total available space in the device chamber 10b is relatively reduced, and the space for the various operational components 22a, 22b, 22c, and 22d is reduced. Accordingly, the efficient assembly of the microwave oven is deteriorated.
Further, according to the safety device of the conventional microwave oven, as shown in FIGS. 2A and 2B, wiring pins 41a and 42a of the first and second switches 41 and 42 are extended inward in the device chamber 10b, while the wiring pin 43a of the third switch 43 is extended toward the door 30. Accordingly, the wiring structure becomes complex, and the assembly of the microwave oven is deteriorated due to the complex wiring process.